Late events and side effects are reported in 392 children cured of leukemia. They originated from 1193 consecutively newly diagnosed children between 1972 and 1982, in first continuous complete remission for at least 6 y after diagnosis, and were treated according to Dutch Childhood Leukemia Study Group protocols (70%) or institutional protocols (30%), all including cranial irradiation for CNS prophylaxis. Data on late events (relapses, death in complete remission, and second malignancies) were collected prospectively after treatment; late side effects were retrospectively collected by a questionnaire, completed by the responsible pediatrician. The event-free survival of the 6-y survivors at 15 y after diagnosis was 92% (+/- 2%). Eight late relapses and nine second malignancies were diagnosed, two children died in first complete remission of late toxicity of treatment, and one child died in a car accident. The most important long-term side effects reported were learning disabilities (50%), short stature, obesity, and delayed pubertal development. No increase in the incidence of cardiovascular, pulmonary, urogenital, or gastrointestinal tract diseases or an increased vulnerability of the musculoskeletal system was found. However, prolonged follow-up is necessary to study the full-scale late effects of cytostatic treatment and radiotherapy administered during childhood.